Antibacterial stainless steel wire and manufacturing method thereof

ABSTRACT

In an antibacterial stainless steel wire and its manufacturing method, a wire drawing process, a cold working process, or a solution treatment integrated with an ageing treatment are used for making a precipitation of copper into an independent phase and in a granular form uniformly distributed in a stainless steel substrate, such that the stainless steel wire has an antibacterial effect.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an antibacterial stainless steel wire and its manufacturing method, and more particularly to a method of using a wire drawing process, a cold working process, or a solution treatment with an ageing treatment to make a precipitation of copper into an independent phase and in a granular form uniformly distributed in a stainless steel substrate, such that the stainless steel wire has an antibacterial effect.

2. Description of the Related Art

R.O.C. Pat. Publication No. 554052 discloses an antibacterial stainless steel, the stainless steel is comprised of over 1 wt % of copper element, and thermal treatment and surface treatment are used to obtain a surface roughness of the stainless steel that falls within a range between 0.09 to 0.5 μm.

In the prior art, a specific copper ratio is used to achieve the antibacterial effect, and the conventional manufacturing method controls the copper ratio or the surface roughness of the stainless steel when the stainless steel is melted, to achieve the antibacterial effect.

Although the surface of the stainless steel has the antibacterial effect after the stainless steel is processed by the surface treatment, the antibacterial effect will be reduced if the surface is worn; or even worse, the antibacterial effect will be lost if the surface is worn out seriously.

R.O.C. Pat. Publication No. 383340 discloses an antibacterial austenitic stainless steel comprising 0.5 to 5.0 wt % of Cu, and 0.1 to 5.0 wt % of Al, and satisfying the condition of Al/N≧5. If necessary, a manufacture induced transformation layer and/or a SiO₂ removal treatment layer is coated onto the surface of a Cu concentrated layer to form an antibacterial layer, and both of the antibacterial effect and the deep stamping property of the austenitic stainless steel and its manufacturing methods have excellent effects.

The aforementioned prior art controls a chemical composition and requires an inorganic coating process, a salt surface treatment and a pickling process.

Since the raw materials are not available easily all the time or the equipment costs are too high, such antibacterial stainless steel incurs a high cost, particularly for the manufacture of antibacterial stainless steel wires, the antibacterial stainless steel is not used extensively.

Further, R.O.C. Pat. Publication No. I240008 discloses a ferrite stainless steel having very good thermal processing and antibacterial effects, and the ferrite stainless steel comprises 0.001% to 0.1% of carbon, 0.2% to 1.0% of silicon, 0.001% to 1.0% of manganese, 11.0% to 20.0% of chromium, 0.001% to 0.1% of nitrogen, 1.0% to 3.5% of copper, balanced iron, and a plurality of microelements indispensable for a steelmaking process, wherein each element is composed of Austenite iron with a value at most equal to 50 in the following formula: γph=420×% C−11.5×% Si+7×% Mn+23×% Ni−11.5×% Cr−12×% Mo+9×% Cu−49×% Ti−52×% Al+470×% N+189, and at least one time of annealing process is processed after the hot rolling process takes place, such that a second phase steel primarily composed of copper (hereinafter referred to as “Copper Phase”) is extracted. The ferrite stainless steel not just has an excellent thermal processing property only, but also provides an antibacterial effect which will not be reduced by the worn-out surface.

In the aforementioned prior art, at least one time of annealing process is performed after the hot rolling process takes place, so as to produce a second phase steel composed primarily of copper and provide the antibacterial effect. However, the manufacturing process and composition are different from those of the present invention.

SUMMARY OF THE INVENTION

Therefore, it is a primary objective of the present invention to overcome the shortcomings of the conventional stainless steel having an antibacterial effect, reduce the manufacturing cost of the antibacterial stainless steel wire.

The present invention provides a manufacturing method of an antibacterial stainless steel wire, and the method performs a wire drawing process to a stainless steel having a copper content greater than 0.8 wt % to manufacture a stainless steel wire with a required external wire diameter, and performs a solution treatment to the stainless steel wire, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C., and finally performs an ageing treatment to the stainless steel wire processed by the solution treatment, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase.

The present invention provides a manufacturing method of an antibacterial stainless steel wire, and the method performs a cold working process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to form a hard wire, and performs an ageing treatment to the hard wire, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase, and finally performs a solution treatment to the hard wire processed by the ageing treatment, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C.

The present invention provides a manufacturing method of an antibacterial stainless steel wire, and the method performs a cold working process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to form a hard wire, and performs an ageing treatment to the hard wire, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase, and finally performs a wire drawing process to the hard wire processed by the ageing treatment, so as to manufacture the stainless steel wire with a required external wire diameter.

The steel type of the foregoing stainless steel is composed of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum.

The present invention provides the aforementioned methods for manufacturing an antibacterial stainless steel wire and has the following advantages and effects:

1. The precipitation of copper contained in the stainless steel wire manufactured by the present invention is in an independent phase and in a granular form uniformly distributed in the stainless steel substrate, so that the antibacterial effect will not be reduced by a worn-out surface.

2. The same antibacterial effect can be achieved for the stainless steel wire, regardless of soft wire or hard wire manufactured by the present invention.

3. The present invention has not added other chemical compositions, and does not require any expensive complicated equipment, so as to save costs effectively.

4. The ASTME2149 antibacterial test of the stainless steel wire manufactured by the present invention shows that the inhibition rates of both Staphylococcus Aureus and Escherichia Coli are up to 99.9%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart of a first preferred embodiment of the present invention;

FIG. 2 is a flow chart of a second preferred embodiment of the present invention;

FIG. 3 is a flow chart of a third preferred embodiment of the present invention;

FIG. 4 is a schematic view of copper formed in an independent phase in a stainless steel wire substrate due to a precipitation, observed in first to third preferred embodiments of the present invention;

FIG. 5 is a schematic view of copper formed in an independent phase in a stainless steel wire substrate due to a precipitation, observed in a first preferred embodiment of the present invention;

FIG. 6 is a schematic view of copper formed in an independent phase in a stainless steel wire substrate due to a precipitation, observed in a second preferred embodiment of the present invention; and

FIG. 7 is a schematic view of copper formed in an independent phase in a stainless steel wire substrate due to a precipitation, observed in a third preferred embodiment of the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1 for a manufacturing method of an antibacterial stainless steel wire in accordance with a first preferred embodiment of the present invention, the method comprises the steps of: performing a wire drawing process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to manufacture a stainless steel wire with a required external wire diameter; performing a solution treatment to the stainless steel wire, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C.; and performing an ageing treatment to the stainless steel wire processed by the solution treatment, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase.

With reference to FIG. 2 for a manufacturing method of an antibacterial stainless steel wire in accordance with a second preferred embodiment of the present invention, the method comprises: performing a cold working process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to form a hard wire; performing an ageing treatment to the hard wire, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase; and performing a solution treatment to the hard wire processed by the ageing treatment, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C.

With reference to FIG. 3 for a manufacturing method of an antibacterial stainless steel wire in accordance with a third preferred embodiment of the present invention, the method comprises the steps of: performing a cold working process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to form a hard wire; performing an ageing treatment to the hard wire, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase; and performing a wire drawing process to the hard wire processed by the ageing treatment to manufacture the stainless steel wire with a required external wire diameter.

The steel types of the stainless steel in accordance with the aforementioned three embodiments are comprised of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum.

With reference to FIG. 4 a schematic view of a test on a stainless steel wire processed with an antibacterial treatment and observed by a backscattered electron microscope in accordance with the first to third preferred embodiments of the present invention, the test shows that the copper is in form of 13 nm grains uniformly distributed in a substrate of the stainless steel wire.

With reference to FIG. 5 for the effect obtained by a first preferred embodiment of the present invention, the observation shows that a precipitation of copper in an independent phase is extracted in the stainless steel substrate.

With reference to FIG. 6 for the effect obtained by a second preferred embodiment of the present invention, observations show that a precipitation of copper in an independent phase is extracted in the stainless steel substrate.

With reference to FIG. 7 for the effect obtained by a third preferred embodiment of the present invention, observations show that a precipitation of copper in an independent phase is extracted in the stainless steel substrate.

An antibacterial stainless steel wire manufactured by the manufacturing method in accordance with a first preferred embodiment of the present invention comprises a copper content greater than 0.8 wt %, and the stainless steel has a steel type composed of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum, and the remaining composites are iron and impurities. The stainless steel goes through a wire drawing process, a solution treatment and an ageing treatment, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C., and the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase.

An antibacterial stainless steel wire manufactured by the manufacturing method in accordance with a second preferred embodiment of the present invention comprises a copper content greater than 0.8 wt %, and the stainless steel has a steel type composed of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum, and the remaining composites are iron and impurities. The stainless steel goes through a cold working, an ageing treatment and a solution treatment, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase, and the solution treatment is carried out at a solution temperature of 950° C. to 1150° C.

An antibacterial stainless steel wire manufactured by the manufacturing method in accordance with a third preferred embodiment of the present invention comprises a copper content greater than 0.8 wt %, and the stainless steel has a steel type composed of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum, and the remaining composites are iron and impurities. The stainless steel stainless steel goes through a cold working, an ageing treatment and a wire drawing process, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase.

From the description above, the present invention integrates the wire drawing process, the cold working process or the solution treatment with the ageing treatment, such that a precipitation of copper is an independent phase as well as a granular form uniformly distributed in the stainless steel substrate, and the stainless steel wire has the antibacterial effect.

In Table 1, the antibacterial test shows that the inhibition rates of the first, second and third preferred embodiments are all 99.9%. It also indicates that each antibacterial stainless steel wire and related products manufactured by the method of the present invention and illustrated by photo taken by a backscattered electron microscope as shown in FIGS. 4 to 6 can achieve the antibacterial effect.

Antibacterial Test: ASTM E2149 Test Result: Quantity of Bacteria (Zero Quantity of hour after Bacteria (Effect inoculation) after 24 hours) Inhibition Rate (CFU/ml) (CFU/ml) (R %) Bacteria Type 1 Staphylococcus Aureus ATCC No. 6538 1.4 × 10⁵ 1.5 × 10² 99.9% Bacteria Type 2 Escherichia Coli ATCC No. 8739 1.3 × 10⁵ <50 99.9%

The steel types of the stainless steel of the present invention include SUS 316J1 SUS 316J1L SUS XM7 and UNS 30430 and AISI 302HQ AISI 304HC 304J3 204CU 201CU 303CU 304ES stainless steels and/or stainless steels with a copper content greater than 0.8 wt %, and/or any stainless steels having a chemical composition falling within this range.

The antibacterial stainless steel wire manufactured by the method in accordance with first, second and third preferred embodiments of the present invention can be used for manufacturing filters, high-pressure soft tubes, steel ropes or needle-shaped products.

While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures. 

1. A manufacturing method of an antibacterial stainless steel wire, comprising the steps of: performing a wire drawing process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to manufacture a stainless steel wire with a required external wire diameter; performing a solution treatment to the stainless steel wire, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C.; and performing an ageing treatment of the stainless steel wire processed by the solution treatment, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase.
 2. The manufacturing method of an antibacterial stainless steel wire as recited in claim 1, wherein the stainless steel is comprised of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum.
 3. A manufacturing method of an antibacterial stainless steel wire, comprising: performing a cold working process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to form a hard wire; performing an ageing treatment to the hard wire, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase; and performing a solution treatment to the hard wire processed by the ageing treatment, wherein the solution treatment is carried out at a solution temperature of 950° C. to 1150° C.
 4. The manufacturing method of an antibacterial stainless steel wire as recited in claim 3, wherein the stainless steel is comprised of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum.
 5. A manufacturing method of an antibacterial stainless steel wire, comprising the steps of: performing a cold working process to a stainless steel with a steel type having a copper content greater than 0.8 wt % to form a hard wire; performing an ageing treatment to the hard wire, wherein the ageing treatment is carried out at a temperature of 600° C. to 800° C. for a processing time of 0.5 hour to 5 hours, such that a precipitation of copper contained in the stainless steel wire is in an independent phase; and performing a wire drawing process to a hard wire processed by the ageing treatment to manufacture the stainless steel wire with a required external wire diameter.
 6. The manufacturing method of an antibacterial stainless steel wire as recited in claim 5, wherein the stainless steel is comprised of 0.01 wt % to 0.15 wt % of carbon, 1 wt % to 4 wt % of manganese, 3 wt % to 12 wt % of nickel, 14 wt % to 22 wt % of chromium and 1 wt % to 3 wt % of molybdenum. 